Ryze is a champion that has a steep learning curve, and you're punished heavily for the slightest slipup. More importantly, higher latency (200+ms) connections basically turn Ryze into an instakill for any bursty enemy, while low (~20ms) latency connections allow Ryze to delete you, if you're good at him.
Some people struggle with Ryze, I did when I first joined and it made me nervous to try him, still haven't to this day.
I think it's important to look at his rank vs the rank the match was in. If he's a newer player to ranked, some of those could be in Qualifiers, which often place you in a higher ranked environment (I got put into S1/G5 Elo for my first 2 matches, then S3-4 for my next 3)